Losing brain enzyme makes mice 'smarter'

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When it comes to brain enzymes, less may be more — at least in mice — suggests research at a Texas university.

Mice with the Cdk5 enzyme knocked out learn faster and detect changes in their surroundings more quickly, say UT Southwestern scientists in a study published this week in the online journal Nature Neuroscience.

"It's pretty rare that you make mice 'smarter,' so there are a lot of cognitive implications," the study's senior author, Dr. James Bibb, said in a news release.

"Everything is more meaningful to these mice," he said. "The increase in sensitivity to their surroundings seems to have made them smarter."

The research may be useful, the scientists suggest, in targeting conditions such as post-traumatic stress disorder, Alzheimer's disease or drug addiction.

The genetically engineered mice were better than their normal relatives at learning their way through a water maze and remembering where they might receive a mild shock. When the maze was changed, the special mice were faster to realize that there had been a change and chart a new course.

While the work is encouraging, Bibb cautions that the long-term effects of removing the enzyme are still being studied.

The scientists say the key to this research was being able to remove the gene for Cdk5 only in the brain and only when the mice were adults. This is a recently developed technique called "conditional knock out" and allows more sophisticated experiments than eliminating the entire gene.